i think ivyleague is right
sure the feds today don't pay so much attention to small family in detroit buffalo etc. but in the 80s when the whole lcn was under radar they did and according to police reports detroit had 30 members or so in the late 80s and there is not any reason to think it's stronger today
the states are not like italy where a mafia family can become stronger in just a few years because they have tons of manpower
how many italians are living actually in detroit? i don't think so many
new york is another history i heard place like staten island have 250.000 italians living there 50% of local population